Bisphenol A linked to sterility in roundworms

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The controversial chemical bisphenol A can render roundworms sterile, kill their embryos, and damage their chromosomes, according to a new lab study.

The findings are sure to re-ignite debate over the health safety of the chemical commonly known as BPA, which is widely used in such consumer products as hard plastic toys, bottles and food container linings.

Geneticists at the Harvard Medical School found that in roundworms exposed to BPA, some DNA repair processes were impaired in the very cells that are essential for the formation of sperm and eggs.

Exposure to the chemical also damaged chromosomal integrity and led to cell death, the authors found. While chromosomes in the control group of roundworms appeared normal, the chromosomes in the group exposed to BPA were frayed and fragmented. That led to embryo death and less fertile worms.

"We show that exposure of [roundworms] to BPA, at internal concentrations consistent with mammalian models, causes increased sterility and embryonic lethality," the authors wrote.

The findings, which are published in this week's Proceedings of the National Academy of Sciences, suggest "a potential mechanism for the effect of bisphenol A on human reproduction," according to notes accompanying the study's release.

The roundworm, C. elegans, is a favourite of researchers because much of its biology is similar to that in humans.

BPA a 'toxic substance'

Previous research has associated BPA with heart disease, diabetes and increased risk of miscarriage in humans. In mice, exposure to BPA has been shown to disrupt the process of cell division.

That's a real concern for many because detectable levels of BPA have been found in 91 per cent of Canadians, with those between ages 12 and 19 most likely to have the chemical in them.

Bisphenol A was added to Canada's list of toxic substances last month.

Two years ago, Canada became the first country in the world to ban the import and sale of polycarbonate baby bottles containing bisphenol A.

Since then, retailers have pulled many products with BPA from their shelves.